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Ask HN: What's Prolog like in 2024?

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Re: Ask HN: What's Prolog like in 2024?

#171

Post by drdeca »

everforward wrote: post #136
jodrellblank wrote: post #116

What is it like? 50 years of historic cruft. Questionable whether there are more trip hazards than usefulness for ordinary coding. A fractured community which feels like there are more Prolog systems than Prolog code. Learning Prolog is less "how do I do things in Prolog" and more "how do I contort my things to avoid tripping over Prolog?". A few dedicated clever people and idealists and dreamers talking about ontolo…

> A few dedicated clever people and idealists and dreamers talking about ontologies and building things I don't understand I was briefly deeply interested in ontologies via OWL and I suspect Prolog has the same issues that I think plague ontologies in general. They are a fantastic tool for a system complex enough to be nearly useless. Modelling an ontology for a reasonably complex domain is unreasonably difficult. No…

I don’t see an issue with saying “X-ray photography machines, and deep-space radio telescopes, are (or at least contains-a, in the case of the telescope) cameras”. They just aren’t ordinary cameras of the sort that a typical person might take a picture with.

I think most of the reasoning you would want to do with a concept of “camera” that excludes X-ray machines and telescopes, but includes night-vision, could be handled with “portable camera”?

Hm, I guess you probably want to include security cameras though..

Ok. “Portable cameras or security cameras”.

Re: Ask HN: What's Prolog like in 2024?

#172

Post by derdi »

triska wrote: post #153
b800h wrote: post #103

Earlier quoted context omitted.

So SWI appears to be more performant, it has an open license, so as per the GGP's claim regarding Scryer in the post above, it must not be ISO-compliant?

A key performance attraction of Scryer Prolog is its space efficiency for representing lists of characters, yielding a 24 times (!) more compact representation than a naive implementation would. With Scryer Prolog and other recent systems that implement this representation, such as Trealla Prolog, we can easily process many GBs of text with DCGs, arguably realizing the full potential of the originally intended use ca…

> adherence to industry standards is of great importance for warranty reasons among others

This is mostly a nice talking point rather than an actual thing, right? Scryer's license contains the usual all-caps NO WARRANTY and NO FITNESS FOR A PARTICULAR PURPOSE wording. Also, the links you provided describe these applications without references to warranties and standards and regulation. The users in these super-sensitive domains don't seem as sensitive about them as you claim.

Re: Ask HN: What's Prolog like in 2024?

#173

Post by hpincket »

I've played around with Prolog on and off for 7 years. Still a novice. It's one of those languages that forces your mind to grow in new directions.

It's difficult to make a case for it. The declarative paradigm is nice, but compared to other languages you're only saving a couple for-loops. I think its benefit comes from expressiveness for problems where clpfd can be applied. I once built an internal tool with Python and SWI Prolog that combined user input with CLPFD to configure test accounts in a consistent and useful way. Users could provide partial constraints, and the system would fill in the rest. Again, the ease of clpfd is great.

I've had some fun generating Prolog facts/databases with LLMs and it's something I want to explore more.

Note: I was just messing around with Prolog this week: https://hpincket.com/adding-an-easter-egg-to-our-numeronym-p...

Re: Ask HN: What's Prolog like in 2024?

#174

Post by triska »

derdi wrote: post #172
triska wrote: post #153

Earlier quoted context omitted.

A key performance attraction of Scryer Prolog is its space efficiency for representing lists of characters, yielding a 24 times (!) more compact representation than a naive implementation would. With Scryer Prolog and other recent systems that implement this representation, such as Trealla Prolog, we can easily process many GBs of text with DCGs, arguably realizing the full potential of the originally intended use ca…

> adherence to industry standards is of great importance for warranty reasons among others This is mostly a nice talking point rather than an actual thing, right? Scryer's license contains the usual all-caps NO WARRANTY and NO FITNESS FOR A PARTICULAR PURPOSE wording. Also, the links you provided describe these applications without references to warranties and standards and regulation. The users in these super-sensit…

> the links you provided describe these applications without references to warranties and standards and regulation.

This is not true. For example, quoting from page 2 of the paper that is linked to in a discussion I posted, An Executable Specification of Oncology Dose-Escalation Protocols with Prolog, available from https://arxiv.org/abs/2402.08334:

"Standards are of great importance in the medical sector and play a significant role in procurement decisions, resolution of legal disputes, warranty questions, and the preparation of teaching material. It is to be expected that the use of an ISO-standardized programming language will enable the broadest possible adoption of our approach in such a safety-critical application area. For these reasons, we are using Scryer Prolog for our application. Scryer Prolog is a modern Prolog system written in Rust that aims for strict conformance to the Prolog ISO standard and satisfies all syntactic conformity tests given in https://www.complang.tuwien.ac.at/ulrich/iso-prolog/conformi...."

Regarding warranty guarantees of Scryer Prolog, may I suggest you contact its author if you need to negotiate arrangements that are not catered for by the only licence terms you currently have access to?

One important advantage you get from the strict syntactic conformance of Scryer Prolog is that it reliably tells you what is Prolog syntax and what is not. In this way, you can use it as a free reference system to learn what Prolog is. The conformance makes it easier to switch to other conforming systems, such as SICStus Prolog which also offers different licences and commercial support, when you need to.

> The users in these super-sensitive domains don't seem as sensitive about them as you claim.

I am at a loss at this phrasing and also about the content of this text. Apart from the facts that I did not use the wording "super-sensitive", and that the importance of standards is explicitly stated in the paper I quoted above, is there even the slightest doubt about the great importance of standards when building and operating giant particle accelerators or devising dose escalation trials in clinical oncology?

Re: Ask HN: What's Prolog like in 2024?

#175

Post by epgui »

7thaccount wrote: post #124
epgui wrote: post #123

Earlier quoted context omitted.

Clojure is probably the most beautiful language I've ever worked with. Nothing is perfect, but Clojure is very simple and elegant.

Only downside is I don't know Java, so some things that should be obvious are opaque to me.

You really don’t need to know any java. I don’t know java either.

Even if you’re doing java interop, it’s quite easy to figure it out.

Re: Ask HN: What's Prolog like in 2024?

#176

Post by 7thaccount »

epgui wrote: post #175
7thaccount wrote: post #124

Earlier quoted context omitted.

Only downside is I don't know Java, so some things that should be obvious are opaque to me.

You really don’t need to know any java. I don’t know java either. Even if you’re doing java interop, it’s quite easy to figure it out.

Last time I looked about file IO it involves calling out to some Java class that I had no clue about as I don't use Java. All the doc of the time just assumed you should be able to figure this all out.

Edit: it's been like 5 years

Re: Ask HN: What's Prolog like in 2024?

#178

Post by nerdponx »

mark_l_watson wrote: post #88
nerdponx wrote: post #75

Earlier quoted context omitted.

How do you normally use Prolog and Python together? I had looked into embedding logic programming within Python in the past, and found a lack of satisfying options, but maybe I didn't know where to look.

I have two short examples in one of my books that I am currently re-writing. Here is a link directly to the Python+ Prolog interop examples https://leanpub.com/pythonai/read#use-predicate-logic-by-cal...

Thank you!

Re: Ask HN: What's Prolog like in 2024?

#179

Post by derdi »

triska wrote: post #174
derdi wrote: post #172

Earlier quoted context omitted.

> adherence to industry standards is of great importance for warranty reasons among others This is mostly a nice talking point rather than an actual thing, right? Scryer's license contains the usual all-caps NO WARRANTY and NO FITNESS FOR A PARTICULAR PURPOSE wording. Also, the links you provided describe these applications without references to warranties and standards and regulation. The users in these super-sensit…

> the links you provided describe these applications without references to warranties and standards and regulation. This is not true. For example, quoting from page 2 of the paper that is linked to in a discussion I posted, An Executable Specification of Oncology Dose-Escalation Protocols with Prolog , available from https://arxiv.org/abs/2402.08334 : "Standards are of great importance in the medical sector and play…

I acknowledge that you also included your nice talking point in a paper you published on arXiv. Citing yourself doesn't convince me any more of the credibility of this argument.

> is there even the slightest doubt about the importance of standards when building and operating giant particle accelerators

The particle accelerator application is a checker for existing JSON config files. The accelerator is already running with those files. The proposed project is in an early stage. The checker will add more assurance, which is nice. The checker's author does not talk about the importance of warranties or standards. The checker could just as well be implemented in some non-ISO dialect as long as that dialect has a reliable specification and implementation.

So yes, there is the slightest doubt.

Edit: BTW, your oncology paper heavily uses CLP(Z), which does not have an ISO standard, so your argument is... The base language must be standardized, but arbitrary nonstandard extensions are OK? Please clarify as I've probably misunderstood.

Re: Ask HN: What's Prolog like in 2024?

#180

Post by YeGoblynQueenne »

vmchale wrote: post #95
radomir_cernoch wrote: post #91

Earlier quoted context omitted.

Do you see a good way to include backtracking in an imperative programming language? I can imagine how unification would work, since the ubiquitous "pattern matching" is a special case of Prolog's unification. But I've never seen how backtracking could be useful...

backtracking is perilous in general; logic programming languages have really nice abilities for such but I don't know how to avoid pathological inefficiency.

With memoization as in tabling (a.k.a. SLG-Resolution):

https://www.swi-prolog.org/pldoc/man?section=tabling

Re-evaluation of a tabled predicate is avoided by memoizing the answers. This can realise huge performance enhancements as illustrated in section 7.1. It also comes with two downsides: the memoized answers are not automatically updated or invalidated if the world (set of predicates on which the answers depend) changes and the answer tables must be stored (in memory).

Known to the Prolog community since about the 1980's if I got my references right.

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